1. Field the Invention
The present invention concerns a biocompatible product containing calcium carbonate and used to cover at least part of a prosthesis in order to integrate the latter into the surrounding bone.
2. Description of the Prior Art
Products containing calcium carbonate are specified by Georges CAMPRASSE in French patents Nos. 2,647,334 and 2,706,308 and the patent application WO 94/17838, in particular for manufacturing shaped parts such as implants and prostheses for orthopedic surgery, or replacement dental roots. These products are made from the mother-of-pearl of aquatic molluscs, for example the mother-of-pearl of Pinctada Maxima, which is subject to a specific mechanical, thermal and chemical treatment. This specific treatment consists in applying to the mother-of-pearl part previously obtained by mechanical preparation of mollusc shells, physical-chemical operations of soaking, washing, rinsing, and steam treatment in the presence of chemical agents, followed by drying at staggered temperatures.
CAMPRASSE products can be particularly used in powder form and have adhesive properties which make them suitable for association with other materials, such as metals or organic polymers, in a biological cement for bedding any prosthesis. The products obtained in this way can be used as a coating on certain metals, rather than a covering integral with the latter, for improved adhesion to the bone tissue.
The CAMPRASSE products can also be used in a compacted form to make a prosthesis itself, for example a tibial plate, a femoral condyl, a hip prosthesis, a screw, etc.
The biocompatible properties of CAMPRASSE products are mainly the result of the composition based on calcium carbonate in the form of both calcite and aragonite. The presence of calcium carbonate in the skeleton of stony corals (order madreporaria), such as Porites, has also lead to the use of the latter, in particular in dental surgery.
CAMPRASSE products have two main drawbacks:
their animal origin makes it very difficult if not impossible to obtain approval in some countries; PA1 their cost is high because of the mother-of-pearl from which they are obtained, which is a relatively rare material, and because of the equipment and labor required for the particular physical-chemical operations required to prepare them. PA1 either an initial substance comprising essentially, by which is meant between 95% and 100%, inclusive, of the weight of the substance : aragonite, calcite, quick lime and hydrated lime, PA1 or an initial substance comprising at least one of the constituents, aragonite and calcite, in a large amount between 10% and 90% by weight of the substance and, if necessary, lime, i.e., quick lime CaO and hydrated lime Ca(OH).sub.2 in smaller amounts, typically 5% to 50% by weight of the substance. PA1 30% to 90% by weight aragonite and 10% to 70% by weight calcite, PA1 50% to 90% by weight aragonite and 10% to 50% by weight quick lime CaO; PA1 50% to 90% by weight calcite and 10% to 50% by weight quick lime Cao; PA1 20% to 80% by weight aragonite, 10% to 70% by weight calcite, and 10% to 50% by weight quick lime CaO; PA1 20% to 80% by weight aragonite, 10% to 70% by weight calcite, and 10% to 50% by weight hydrated lime Ca(OH).sub.2 ; PA1 80% to 95% by weight aragonite and 5% to 20% by weight hydrated lime Ca(OH).sub.2 ; and PA1 80% to 95% by weight calcite and 5% to 20% by weight hydrated lime Ca(OH).sub.2. PA1 1) 30% or 90% aragonite and 70% or 10% calcite, respectively; PA1 2) 50% aragonite or calcite with 50% quick lime CaO; or 90% aragonite or calcite with 10% quick lime CaO; PA1 3) 80% aragonite, 10% calcite and 10% quick lime; or 20% aragonite, 70% calcite and 10% quick lime; or 30% aragonite, 20% calcite and 50% quick lime; PA1 4) 90% aragonite or calcite with 10% hydrated lime Ca(OH).sub.2.